Choke assemblies are used to help regulate the pressure within a well as it is being drilled and stimulated. During such drilling, and particularly during stimulation, high pressure gases and drilling fluids may blow through the choke assembly, bringing sand and other debris which erode the interior of the choke assembly.
Replaceable inserts have been used to line the interior components of the body of the choke assembly and to function as a choke seat. Such inserts are often made of an erosion-resistant material, such as tungsten carbide and some are further lined with an additional erosion-resistant material or tiles. Many prior art inserts are retained within the choke assembly by a snap ring or other separate attachment devices, such as pins. A separate valve seat may be retained within the insert. Often, the high velocity fluids erode the retention components, requiring that the snap rings or pins be replaced and the snap ring retention grooves reformed into the choke interior. This causes additional material and labor costs to repair the choke assembly, as well as losing use of the choke assembly during the time required to make such repairs. Additionally, the retention ring or pin may not fit properly within the refurbished groove or receptacle, thereby causing additional repair time.
Other prior art trim inserts are retained within the choke assembly by a threaded interface between the trim insert and the discharge channel of the choke assembly. Small particles and drilling fluid can accumulate between the trim insert and the choke assembly, including the small area between the threads. This accumulation can cause the threads to erode as well as increase the difficulty of removing the trim insert.
Other prior art replaceable trim inserts have included a flange that positions the trim device within the choke outlet channel. However, the seat against which the valve rested to stop flow through the choke has been a separate device that fit within the trim device.
A As fewer components results in less downtime and fewer problems with assembly of the components, it would be an improvement to the art to have a replaceable insert that is retained within the choke assembly without the use of additional pieces, such as snap rings or pins. It would be a further improvement to the art to incorporate the seat for the valve, or shuttle as it is also called, into the trim component to result in a single piece that may be retained within the choke assembly and provide a seat for the shuttle.